1. Field of the Invention
The present invention generally relates to manufacturing methods and evaluating methods of magnetic recording media, and more specifically, to a manufacturing method and evaluating method of a magnetic recording medium having a lubricating layer.
2. Description of the Related Art
In recent years, a magnetic storage device such as a magnetic disk device has been and being used in a wide range as a storage device of a motion picture or music. Especially, the magnetic storage device is used for recording motion pictures for home use. The magnetic storage device has a high speed access, a small size, and a large capacity and therefore the market size of the magnetic storage device is increasing instead of a conventional video device for home use using a video tape. Since the amount of information of the motion picture is large, it is required for the magnetic disk device to have a large capacity. Because of this, in order to further improve recording density that is increasing at 100% per year, improvement of technology for higher recording density of a magnetic head and a magnetic disk is required.
As a method for achieving the high recoding density, making the floating height of the magnetic head low is progressing. The floating height is the minimum distance between the medium facing surface of a head slider of the magnetic head and the magnetic disk surface. By reducing the floating height, it is possible to make the distance between a recording element and a regeneration element of the magnetic head and a recording layer of the magnetic disk small. As a result of this, a recording magnetic field having greater strength can be applied to a recording layer and a signal magnetic field from the recording layer can be detected in a stronger state.
A protection film or a lubricating layer is formed on the surface of the magnetic disk so as to cover the recording layer. The protection film or the lubricating layer prevents damage of the recording layer from undesirable impacts by the magnetic head.
In order to inspect for mechanical strength of the protection film, evenness of film thickness of the lubricating layer, or securing stability of the lubricating layer or the protection film, there is a CSS (Contact Start and Stop) test, a load and unload test wherein the magnetic disk is rotated so that loading and unloading of the magnetic head is repeated, a seek test wherein moving (seeking of) the magnetic head is repeated between the internal circumference and the external circumference of the magnetic disk, and an accelerating test for implementing these tests in an atmosphere of high temperature and high humidity.
Through these test, quality of the magnetic disk is determined by checking for existence of damage of the disk surface or dirt on the medium facing surface of the magnetic head. Optical microscopes have been used for seeing the dirt of the medium facing surface of the magnetic head. See, for example, Japanese Laid-Open Patent Application Publication No. 62-167618.
In the meantime, since a frictional wear powder of the protection film adhered to the medium facing surface of the magnetic head looks like a black lump through the optical microscope, it is possible to easily see it.
However, it is difficult to see a liquid state hyaline lubricant through the optical microscope. Therefore, even if a large amount of the lubricant is adhered, it is difficult to make proper determination. The adherence of the lubricant on the medium facing surface influences the floating stability of the magnetic head. The more the floating height is reduced, the greater the degree of the influence becomes.
As a method for evaluating the amount of the lubricant, there is an ESCA (X ray electron spectroscopy) method or an FTIR (Fourier transform infrared spectroscopy) method. However, these methods are evaluating methods of the magnetic disk. Although it is possible to directly see the amount of adhesion of the lubricant on the medium facing surface by the ESCA (X ray electron spectroscopy) method or the FTIR (Fourier transform infrared spectroscopy) method, a concave and convex part such as a pad or groove is formed on the medium facing surface and therefore the medium facing surface is not flat. Hence, focusing should be done frequently and therefore measurement of the amount of lubricant is complex and difficult. In addition, measurement of the distribution of the amount of the lubricant adhered on the medium facing surface is extremely difficult.